Questions tagged [iterator]
An iterator is an object-oriented programming pattern which for the most part functions similarly to a pointer to an object inside a collection with the added ability to traverse through the collection in a defined manner, agnostic of the actual implementation or even object addresses in physical memory. Iterators may be further limited in particular traversal directions.
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Replace values in R data frame according to values in other data frame
I would like to change row names values from a first data frame if these rows names are present in another data frame, and change it to a corresponding value (defined in the second data frame). I ...
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Most efficient way to loop through files using VBA Excel
I have a procedure for looping through all files in folders and subfolders starting at a folder which the user can select. The user can select both the source and target folder. I'm using Excel VBA ...
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Rust Iterator that correlates a slice with itself
In my effort to learn Rust I've tried implementing an Iterator that splits up a buffer in two halves, and correlates both halves by sliding them over each other with different positions (lags). You ...
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Sequence for Pre-order traversal of Binary Trees
I wanted to make a Sequence that can do a pre-order traversal of Binary Tree. Doing so provides automatically unlocks wonderfully useful methods, like ...
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Simple linked list with two iterators
As part of the practice, I created minimalist linked list named SimpleList which can be iterated in two different ways: one element after another or by every second ...
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4answers
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Count all vowels in string
For a homework assignemnt, I was asked to complete this CodeStepByStep problem. It's coded correctly and gave me a right answer. I'm just wondering if there's an easier way to solve this problem ...
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Combining arbitrary number of lists inside json
I have some JSON where each key stores an array, and I need to combine all those arrays into a single array. My current solution doesn't seem the most friendly to review, but without ...
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1answer
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Speed up fast poisson disk sampling generator in Python
I wrote a generator class which implements Fast Poisson Disk Sampling algorithm in Python. I did some optimizations like, x ** 2 -> x * x, using unpacking ...
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Linked list implementation C++
I hope this is the right way of doing things: I've previously posted a request for a code review and gotten feedback. Now I have new improved code that I would like a code review on again. Old: C++ ...
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2answers
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C++ linked list iterator implementation
I'm a first year computer engineering student and would appreciate feedback on some code.
I've created a linked-list with an iterator to be able to range for loops like: ...
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1answer
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Optimizing quicksort
I created simple quicksort algorithm using iterators. I'm happy with implementation but not with its speed. Profiler tells me that the slowest operation here is ...
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itertools.produce reduced and filtered
I need to generate list of all allowable test combination values of of actor, action and ...
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Decoding assembly instructions in a Game Boy disassembler
I am coding a game boy disassembler in C++. The program (simplified here) converts a vector of byte into an assembly instruction and print it.
To do so, it iterates through the vector of bytes (char)...
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1answer
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Short analogue of Riffle[] accepting two blocks
I have an array of some elements that I need to loop through (i.e. execute some block A on each element) but between them I have also to "clean up" (block ...
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1answer
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Merging (not removing) duplicated elements in a vector
There's a struct named Player containing name and stat:
...
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2answers
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A Java Iterable over multiple arrays
GlueArrays is used for iterating over an array of arrays, and it looks like this:
Main.java
...
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2answers
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Infinite and countdown counters
I'm refactoring my scheduler and for one of its triggers I need an endless counter that would automatically restart. Since this is a simple and very common task I don't want to ever have to implement ...
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My implementation of a for_each function that traverses a std::container by some step size integer N
As my answer to Iterating over an odd (even) elements only in a range-based loop, I wrote this function, with the following driver program and output:
...
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1answer
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Rust version of basic functional prime stream - can this be made less clunky?
I'm looking at implementing the basic functional not-quite-Eratosthenes prime stream in Rust. I like to try it when I start learning a language.
Here's the bog standard Haskell version:
...
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1answer
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Find all starting indices in a string which are anagrams of a word
The task:
Given a word W and a string S, find all starting indices in S which
are anagrams of W.
For example, given that W is "ab", and S is "abxaba", return 0, 3, and
4.
My solution:
...
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1answer
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Iterating over different Objects which are ordered by index number
I am currently working on a bigger project where I found a part of it which seems very ugly to me from the code.
I stripped out the algorithm and made a working code, so it can be reviewed.
I have ...
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1answer
283 views
Applying multiple php FilterIterator instances in a cascading fashion
I wrote an implementation of php FilterIterator objects that allows me to apply them in a "cascade" way, so I can finally obtain an array of objects which is the ...
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An iterator returning all possible permutations of a list in Java - follow-up
(See the previous and initial iteration.)
My main attempt here was to get rid of monolithic code and split the implementation into smaller methods when applicable and do more extensive commenting. ...
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3answers
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Python generator for “barely obtuse” triangles (Project Euler 224)
I am trying to solve Project Euler Problem 224:
Let us call an integer sided triangle with sides a ≤ b ≤ c barely obtuse if the sides satisfy a2 + b2 = c2 - 1.
How many barely obtuse triangles ...
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2answers
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Python grouped iterator
I wanted to write an iterator that would split items up into groups, so i can bulk insert into mysql without crashing or overwhelming the server.
This is the implementation I came up with.
I am ...
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0answers
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Iterator that groups elements of its source
I wrote an iterator to access the pixel in an packed image.
It works, but it is slow.
1.Are there any mistakes that can be avoided and might lead to better speed?
2.Are there any pitfalls that ...
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1answer
50 views
Class representing digital PLC address
I have a project where I work with digital addresses for a Programmable Logic Controller (PLC). The requirement is that the user gives a start address e.g. 1000.0 and then for example the next 20 ...
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2answers
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Finding the common iterator category in C++
I created a template trait which finds the common iterator category between a set of given iterator categories. More specifically, it's a class with a member type alias to one of the iterator tags ...
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1answer
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Finding the Original Fractions from Rounded Decimals
The data I'm using is summoning rates from a gacha game, One Piece Treasure Cruise. The game provides the probability of getting a certain character in percents rounded to the nearest thousandth. ...
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2answers
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Walking directory tree like python does
I like python's os.walk and I was missing it in C#. It's a very convenient API so I thought I create my own utility that does something similar.
The original API ...
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1answer
231 views
back_inserter for several container arguments
Recently I wrote a back_inserter with the same interface as the std::back_inserter just for supporting several containers in the constructor and doing push_back for each. The solution needs C++17. ...
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1answer
61 views
Convert a type u16 number to a matrix (Vec<Vec<u8>> or array) of 4 x 4
I am a Rust newbie and I am not familiar with all the iterator options. This is what I have so far. How can I make this better or at least avoid collecting twice into a Vec?
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1answer
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Check if an element exists in a list of dictionaries [closed]
The logic of the code to build was as follows, two logical conditions; If the value of dictionary element matches in the list of dictionaries return the particular dictionary, and if no element ...
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1answer
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Deferred Iteration in TypeScript
I've published a new TypeScript library currently in beta, and was hoping to get feedback on certain aspects of it, particularly implementation details for improving the performance of deferred ...
6
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1answer
59 views
General nested for
I needed a general-purpose function that accepts some sequence_container<sequence_container<T>> and iterates all permutations of the inner container. To ...
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3answers
168 views
Progress bar wrapper class in C++
I've recently written a simple progress bar class in C++ to mimic usage of similar libraries I've used in Python. The idea is to take some iterable container (e.g. ...
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4answers
770 views
Take a desired string, iterate through objects to see if it exists in a given field and append a number until a unique string is found
I wanted to in the most generic way possible write a method in C# to achieve the following.
Take in a string, a set of objects, and a function to access the field of a given object
Look at all of the ...
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1answer
108 views
Handling related generic type parameters
In answering a question on StackOverflow, it occurred to me that a more generic version of GroupBy for C# that delegated membership in each group to a class could ...
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1answer
309 views
putting sql-query response directly to foreach-loop?
Is there any reason to not do this?
Putting the query directly inside a foreach-statment when the only time the result is going to be used is within that location.. ...
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4answers
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Basic iterator supporting vector implementation
On the fly, I just implemented this iterator supporting vector class to understand how range-based for loop works.
It's really basic but let me know what can be improved.
Vector.h
...
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3answers
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Endless stream: stream a range and return default value if the range is exhausted
Introduction:
Motivation
Sometimes there is a need to merge N > 1 ranges, and they don't have equal length, but there is a value which can be used in case the range is already exhausted. It is ...
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Iterator for BFS binary tree traversal
I implemented an iterator pattern for C# using IEnumerator and IEnumerable. The goal of the implementation is to traverse a ...
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2answers
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Iterable object on set of ids
For some of the algorithms that I am implementing it turned out to be useful storing ids in order to iterate on objects, while also avoiding having to think about reallocation and invalidation of ...
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4answers
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Implementing a custom iterator by inheriting from an existing iterator class and overriding operator*
My goal is to write very little code and I want a custom iterator that only changes the behavior of the dereference operator* but copies the rest of the behavior ...
4
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1answer
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General use multi-dimensional container using operator[]
This is a followup to a previous question of mine on same subject.
Context
I want to have a tool that allows to simulate as much as possible a C++ standard container for a multidimensional ...
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1answer
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Getting serial port list
Needed to get a local serial port list. System.IO.Ports.SerialPort.GetPortNames() returns names but not the descriptions like you can see in Device Manager: ...
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1answer
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Flatten nested iterables
I wrote a program sometime ago that reads csv files, sorts, reorders and groups their columns/rows' content (with itertools) and later labels the groups using a ...
